Use Sprint locked iPhone with "bad ESN" overseas?

Hi guys,

Im thinking about purchasing an iPhone 5C from ebay (US) - shop called "thegeex". Unfortunatelly the phone has got bad ESN and its locked on Sprint carrier. However I was told, that it should work fine overseas (Europe).

Is it true or do I have to pay for some "factory unlocking" etc.?

Thanks guys!

see: http://www.ebay.com/itm/Apple-iPhone-5C-Latest-16GB-White-Sprint-WARRANTY-100-WO RKING-BAD-ESN-/141202263400?pt=Cell_Phones&hash=item20e04f8d68
"(BAD ESN) - This means the device CANNOT be activated on its original carrier: Sprint "